苹果砧穗组合幼苗对干旱胁迫的生理响应及其抗旱性评价OA

Drought stress,as a key abiotic factor restricting apple cultivation,significantly affects the physiological metabolism of fruit trees and the commercialization of fruits.This study aimed to evaluate the drought resistance of apple rootstock-scion interaction systems through multi-dimensional physiological indicator analysis and comprehensive membership function analysis,to provide theoretical support for optimizing apple cultivation techniques in arid areas.Eight one-year-old apple rootstock-scion combinations(XM7,X5M7,XG,X5G,XMT,X5MT,XW,X5W)were used as test materials and subjected to continuous drought treat-ment.Measurements were taken after 0,4,8,12,16,20 and 24 days of treatment,including leaf relative e-lectrical conductivity(REC),contents of malondialdehyde(MDA),soluble sugar(SS),soluble protein(SP)and chlorophyll(Chl),and activity dynamics of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT).Correlation analysis and principal component analysis(PCA)were performed on the meas-ured indicators,followed by the comprehensive evaluation on drought resistance of each apple rootstock-scion combination using membership function analysis.The results were as follows.(1)With prolonged drought stress,the leaf chlorophyll content of the eight apple rootstock-scion combinations continuously decreased,with a reduction of 21.21％to 44.97％compared to the control.electrical conductivity,and the contents of MDA and SS showed linear accumulation,with increases of 144.62％to 168.91％,93.51％to 128.51％,and 41.20％to 112.85％,respectively,compared to the control;the soluble protein content and SOD,POD and CAT activities firstly increased and then decreased,peaking between the 8th and 16th day of stress.(2)There were significant correlations among key indicators:CAT activity was significantly positively correlated with SOD activity and soluble protein content,while POD activity was significantly negatively correlated with chlo-rophyll content,and relative electrical conductivity was significantly negatively correlated with soluble protein content.(3)Through principal component analysis,two principal components were extracted,explaining 85.66％of the variance information.Based on the comprehensive drought resistance index(D value)construc-ted from the PCA results,the drought resistance of the eight apple rootstock-scion combinations were se-quenced as XW＞X5W＞XMT＞X5MT＞X5G＞XG＞XM7＞X5M7.The XW combination(using Malus sieversii as rootstock)showed significant advantages in drought-resistant cultivation.The results of this study could provide theoretical references for rootstock combination selection and orchard water management in apple.